This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic biofilm infections in the lungs of cystic fibrosis patients. During colonization of the lung, P. aeruginosa converts to a mucoid phenotype characterized by the overproduction of the exopolysaccharide alginate. Exopolysaccharides are the major component of bacterial biofilms and are believed to be produced and secreted by multiprotein complexes spanning the cell envelope. The exopolysaccharide is believed to be secreted across the outer membrane by a porin, AlgE. Understanding the structure of AlgE and how it facilitates transport of the polysaccharide and interacts with other members of the secretion complex will be critical to our long term goal of developing novel methods to disrupt exoplysaccharide biosynthesis and therefore biofilm formation.